Sheet Intrusions and Fluid Transport (ShIFT)

ShIFT will transform how we include solidified sheets of magma (intrusions) in computational models used to predict subsurface fluid flow through rocks. Such models are crucial to exploring for and managing groundwater and geothermal resources, and suitable geological storage sites in many areas worldwide. By driving a step-change in the predictive capability of subsurface fluid flow models, ShIFT will reduce risks, costs, and waste of these activities, ensuring a sustainable impact in keeping people prosperous, safe, and secure. Understanding how fluids move through and are stored in rocks is critical to the energy transition and several UN Sustainable Development Goals (SDG). Over 50% of people rely on groundwater for domestic use. Future-proofing groundwater supply requires securing new and sustainably managing resources (SDG 6). Subsurface fluids also drive geothermal systems and affect the safety of underground storage sites for gas, captured CO2, and radioactive waste (SDG 7, 13). Predicting subsurface fluid flow is thus key to many Earth Science disciplines and industries. Computational models that capture an areas subsurface geology and simulate its control on fluid flow are crucial to this prediction. Interconnected networks of ancient, igneous sheet intrusions transect the subsurface in many areas. Currently we model sheet intrusions as simple, continuous, planar structures that restrict fluid flow. However, most sheet intrusions comprise multiple segments, often separated by slithers of host rock; these slithers can act as bridges for fluids to flow across. Segment geometry also controls the: (1) formation of fractures within sheet intrusions, which fluids can flow through; and (2) local damage and heating that alters the physical properties of adjacent host rock and positively or negatively impacts fluid flow. To properly input sheet intrusions into fluid flow models we need to capture their segmentation and incorporate their internal fracturing and local host rock changes. Yet we often lack the subsurface data to fully describe sheet intrusion networks, or their effect on the host rock. To solve this issue, ShIFT will develop predictive methods to estimate these from limited subsurface data by: Measuring sheet intrusion segment geometries and the distribution of host material changes observed in outcrop, seismic reflection data, and physical models. Collecting samples and using laboratory experiments to measure their fluid flow properties. Using microscope techniques to examine the grain-scale changes that enhance or restrict fluid flow and identify their underlying causes; this knowledge is essential for the prediction of changes at a range of depths and temperatures. We will analyse sheet intrusions with different compositions, sizes, and host rock types. With these data we will establish empirical equations that relate aspects of sheet intrusion geometry (e.g., length and thickness) and associated host rock changes. These relationships will enable us to estimate segment shape and size, as well as changes to rock properties, from limited knowledge of an areas sheet intrusions and host rock lithology. ShIFT will use this information to build novel Finite Element numerical models that capture sheet intrusion segmentation and host rock complexity. We will create synthetic but realistic models that simulate the effect of sheet intrusions on fluid flow in different geological scenarios. Our work will enable a step-change in fluid flow modelling, leading to improvements in the exploration for and management of groundwater and geothermal resources, and storage sites for clean gas, CO2, and radioactive waste.